A common problem in the oil field is the loss of circulation of special fluids, such as drilling, cementing, completion and workover fluids, into highly permeable zones of the subterranean formation or into the wellbore. Loss of wellbore fluids into the formation or wellbore can dramatically increase the costs of such operations. Such increased costs may be attributable to damage to the drill bit caused by overheating, a decrease in the drilling rate, blowout due to a drop in fluid level in the well, zonal isolation failure due to insufficient cement filling and requisite remedial operations. In some instances, loss circulation fluids may cause the collapse of the formation at the wellbore as well as in-depth plugging of the formation. This, in turn, may cause such extensive damage that the reservoir may have to be abandoned.
In order to stop or retard the flow of undesirable fluids into the formation, it is desirable to form a barrier in the formation. Such barriers plug the passages responsible for fluid flow. Often, lost circulation materials (LCMs) which are capable of bridging or blocking seepage into the formation are added to the fluid. While cements and silicates are frequently used as LCMs, the flow properties of such fluids often do not achieve effective plugging. For instance, the large particle size of cements often prevents LCM compositions containing cement from penetrating much beyond a few centimeters into low flow rate channels. Alternatives are desired which will allow LCM compositions to penetrate further distances into such channels.
Further, when cements are used in high flow rate channels, the set time of the cement, in relation to the flow rate, often prevents stoppage of the loss of circulation. Barrier plugs having cement as LCMs are thus frequently ineffective to the influx of wellbore fluids. More effective methods for reducing the loss of wellbore fluids into flow passages of the formation, as well as in the wellbore, during well treatment operations, such as during drilling, cementing, completion or workover of the well are therefore desired.